Luis Elizondo led the US Department of Defense Advance Aerial Threat Identification Program (AATIP) which ran from 2007 to 2012 at a cost of £16 million.

In October, after resigning from the department to join a UFO research group he was behind the release of two videos caught on US Navy pilot radar cameras.

He pointed out that the “inexplicable craft” moved in ways which defied physics.

One of the military radar videos was filmed off the coast of San Diego in November 2004 by US Navy pilots who described seeing several while UFOs shaped like the sweet Tic-Tacs.

The case became known as the Nimitz UFO incident.

However, the video has since been branded a wrongly identified plane by several skeptics – prompting Mr Elizondo to reveal there is more to come, including video recordings of encounters with "unknown technology that is far more advanced than anything in the US military."